Some years ago, there was a Mensa convention in San Francisco .

Several of the Mensa members went out for lunch at a
local cafe. When they sat down, one of them discovered that their salt
shaker contained pepper, and their pepper shaker was full of salt. How
could they swap the contents of the two bottles without spilling any,
and using only the implements at hand?

Clearly -- this was a job for  Mensa minds. The group debated the problem
and presented ideas and  finally, came up with a brilliant solution involving a
napkin, a  straw, and an empty saucer.

They called the waitress over, ready to dazzle  her with their solution.

"Ma'am," they said, "we couldn't help but notice
that the pepper shaker contains salt and the salt shaker " But before
they could finish, the waitress interrupted. "Oh -- sorry about that."

  She leaned over the table, unscrewed the caps of both bottles and
switched them.

There was dead silence at the Mensa table.

 

The grapes are sour, no doubt.